This invention relates to a printer such as a laser beam printer.
An image recording device is known, which utilizes an electrophotographic system in which a surface of a photoconductive drum is exposed to light to form a latent image on the drum surface. Toner is then applied to the latent image to develop the image, and the developed image is transferred onto a recording sheet and is fixed by a fixing unit. Such an image recording device is chiefly employed in a copying machine. In recent years, however, the image recording device is being utilized in a printer or the like, for printing output from a computer. One such printer is a laser beam printer.
The laser beam printer comprises, for example as illustrated in FIG. 1, a photoconductive drum 1. Arranged about the photoconductive drum 1 in due order in a rotational direction thereof are a charging station A, an exposure station B, a developing station C, a transferring station D, a toner-cleaning station E, and a discharge station F.
The arrangement is such that at the exposure station B, the laser beam scans the surface of the drum 1 which has been uniformly charged at the charging station A, to thereby form a latent image on the charged drum surface. Toner is then applied at the developing station C to the latent image to develop the same. Subsequently, the developed toner image is transferred, at transfer station D onto the recording sheet P, which travels at a velocity identical with the circumferential speed of photoconductive drum 1.
The recording sheet P carrying the toner image transferred thereon at the transfer station D is guided and/or fed by guide rollers to fixing station G. The recording paper P is then heated and/or pressed at fixing station G for the toner image to be fixed on the surface of the recording sheet P.
The constitution of the laser beam printer is principally similar to that of an electronic copying machine except for the exposure station. Actually, principal parts of the electronic copying machine are often commonly used for conventional laser beam printers.
The electronic copying machine is designed so that an image-carrying surface can instantly be viewed by transferring the toner image onto the upper surface of the recording sheet and discharging the recording sheet with the image-carrying side up (so-called "faceup exhausting"). This naturally results in the fact that the faceup discharging system is employed in the laser beam printer having the principal parts in common with the electronic copying machine.
However, printers are normally used to print onto sheets on a continuous baises and, if the sheets are discharged with the image-carrying surfaces up, they will be stacked in inverted order of pages.
What has been heretofore proposed to overcome the above defect is that the recording sheet is turned upside down before being discharged by guiding the recording sheet along a sheet discharge path extending from the fixing station, inside the printer, to the same side as the sheet introduction side.
However, with the aforementioned arrangement, the recording sheet feed path inside the printer becomes long and complicated, which causes jamming and other similar problems. Further, the printer tends to become large-sized.